Mozilla Developers Remove Critical Bugs

The Mozilla Foundation has removed at least ten vulnerabilities from its browser, three of which were classified as critical by the developers.

One of the critical bugs gave attackers the ability to execute Javascript with chrome privileges. The bug report MFSA 2008-03 also mentions a vulnerability in the "XMLDocument.load" function which could be exploited to inject Javascript into a frame outside the original frame and thus work around the browser's same origin policy.

The Mozilla developers discovered various bugs in the Mozilla Browser Engine; although they are not described in more detail it is understood that they were capable of crashing the browser and thus giving attackers the ability to inject and execute malicious code. The bug described in MFSA 2008-01 also affects the Thunderbird mail client. The next version of Thunderbird will include a fix.

The third critical vulnerability, MFSA 2008-06, gave attackers the ability to parse the browser history via a "designMode" frame on a manipulated website. The attack could crash the browser thus giving attackers the ability to inject malicious code. MFSA 2008-10 desccribes another vulnerability caused by Javascript which allowed for URL hijacking using the "302 Redirect" function in HTML code.

The vulnerabilities described here can be avoided by temporarily disabling Javascript. The Mozilla Foundation's Security page describes these bugs and other security-relevant issues. Besides the Firefox browser, Seamonkey and Camino are affected. An updated version of Firefox (version 2.0.12) is available from the Mozilla servers. Distributors are likely to release updated packages in the next few days. Version 1.1.8 of the Seamonkey browser suite is also available for downloading.

Following security fixes for Firefox, Camino & Co, the developers of the Thunderbird email client have now taken steps to remove known vulnerabilities, closing down five security holes, one of which was and classified as critical.